And with about 600,000 iPad2 units sold in the first three days of shipment – roughly twice as fast as the original – the iPad can now officially take its place in the pantheon of celebrated phenomena alongside the hula hoop, the Rubik cube, Elvis, Marilyn, Beatlemania, Bieber Fever et al.

Faster than you can say “I gotta have it” Apple’s iPad2 flew off the shelves on Friday and Saturday, dashing any notion (as well as the hopes of more than a few competitors) that the device and the public’s appetite for it has waned in the past year.

The iPad2 was out of stock at every one of the over three dozen Apple Retail stores that I phoned over the last 72 hours. The phone lines were jammed and I spent about five to 10 minutes typical in the busiest locations.

All of the beleaguered Apple Geniuses who answered the phones during my informal spot check of the over 200 Apple Retail stores nationwide told the same tale. Their respective inventories of the iPad2 tablets sold out within hours of going on sale Friday. The lucky ones – usually located in busy states like California, Florida, Illinois, Massachusetts, New Jersey, New York and Texas — got a second shipment on Saturday, only to have those fly off the shelves in short order, too. About one-quarter of the Apple stores I called said they were expecting/hoping for new shipments on Monday or Tuesday, while the rest simply didn’t know and just instructed me to call back and keep checking. The Apple Geniuses were also in the dark about how many of the iPad2s they were scheduled to receive but several disclosed that they planned on opening at least an hour earlier to handle the anticipated crush of customers.

Lead times for online orders for all iPad2 models: the 16GB, the 32GB and the 64GB WiFi and WiFi+3G are all running three to four weeks in advance, according to Apple’s Website. If the demand continues at this rate, it’s very possible that the backlog could grow to six to eight weeks.

So what’s fueling the Apple iPad2 adulation? And can any of Apple’s tablet rivals make a perceptible dent in its unit shipments and market share?

Apple set the bar high for itself when the original iPad was a runaway success selling over 15 million units from April through December 2010. Apple knew it had to top itself and stay ahead of competitors like HP, Motorola, Google and Toshiba which are all hot on its heels to take a bigger bite out of the iPad2’s market share.

The iPad2 incorporates a dual core A5 chip for faster Web surfing and improved multitasking capabilities; 9x faster graphics and 10 hours of battery life. The latter is welcome news for road warriors – whether you’re traveling on business or packing the kids in the car for a long drive to visit Grandma or your favorite vacation spot. It’s also equipped with two cameras – front and back that are optimized for FaceTime video calling. The cameras work in concert. The front camera lets you exchange greetings face-to-face with friends or colleagues and you can use the back camera to pan to your surroundings while you’re engaged in the video chat. The cameras also let you film in HD.

Apple, whose early Macintoshes were always among the most costly computers on the market, has sagely adopted a more aggressive pricing strategy. The new and improved iPad2 costs the same as the initial 1.0 model. Prices start at $499 for the basic 16GB WiFi model and go up to $829 for the 64GB WiFi+3G versions. Apple has thrown down the gauntlet, challenging rivals to match it feature-for-feature at the same price points.

Problems in Paradise: iPad2 Light Leakage

Dozens of users the Apple support forum have already reported “slight to significant” white and yellow light leakage on their iPad2s on both the display area and around the bezel. The leakage is visible in dark rooms and low lighting; in natural or bright light it appears as blotches on the display screen but is generally much less noticeable. While a certain amount light leakage is common in smart phone and tablet devices (this flaw also occurred in the original iPad as well as the iPhone ), and a percentage of light leakage problems resolve themselves with use, that’s not always the case if it is a severe manufacturing defect.

Users on the Apple support forum were miffed at the extent of the leakage, which they deemed unacceptable. Their disappointment was magnified by their current limited choices: they can either return the affected tablets to the Apple stores for a refund or they can exchange it. However, since the overwhelming majority of the retail outlets are sold out, the users face the prospect of waiting for days or weeks for a replacement. And there’s no guarantee that the replacement iPad2 tablets won’t have the same defect.

So far there’s no official word from Apple on the cause or extent of the light leakage problems or what it is doing to resolve the issue. However, the Apple Geniuses that I spoke to at various retail outlets were aware of the issue and said they would refund or replace any defective units.

What is known is that Apple used Apple used a different manufacturing method to attach the iPad2 display screen to the unit than it did with the original iPad model. The first iPads that shipped in 2010 held the screen in place with clips. The iPad2 displays are connected to the unit with bonding agents. Speculation is rife that because the demand is so high that the iPad2s, which are manufactured in China, are shipping at such an accelerated rate that the bonding agent hasn’t had sufficient time to dry.

Some inventive users have already devised nostrum remedies. One reported that he put a couple of good sized books on his device overnight to speed up the “bonding” process while another left his device in the freezer for a few hours to similarly make the display stick and minimize the leakage.

With a few notable exceptions, users that bought the iPads last Friday, experienced the light leakage and opted to return them, praised Apple for excellent customer service in taking the devices back and exchanging them (when replacement units were available). One angry customer did report that the Apple Genius at his local retail outlet told him that the light leakage was “a feature of the iPad2.” Yikes!

Overall though, while these early iPad2 adopters were disappointed, most opined that they like the Apple products so much that it wouldn’t stop them from using them. Interestingly, I didn’t see or hear of any posters that said they intended to switch to another tablet device. Apple versus Tablet Rivals: Nolo Contendere That brings us to the inevitable question: since users have an ever increasing array of tablets from which to use, will any, some or all of them defect from Apple’s iPad in substantial numbers?

The answer for at least in the short term appears to be a resounding “No.” It’s been over a year since Apple first unveiled the iPad and jump started what had been a stagnant tablet market. Since then, some very strong competitors with their own feature rich offerings in a variety of configurations from 5 inch to 10 inch displays at varying price points from under $200 to $1,000 (US dollars) have entered the market. These include: the Research in Motion (RIM) Blackberry PlayBook, the Dell Streak, the Hewlett-Packard HP TouchPad, the Lenovo IdeaPad, the LG G-Slate, the Motorola Xoom, the Samsung Galaxy Tab, the Sony Dash and tablets running Microsoft’s Windows 7 operating system that are aimed at businesses.

Despite the veritable onslaught of competitors with deep pockets and aggressive counter-marketing campaigns, the iPad remains the tablet of choice. It far outpaces rivals with close to 20 million units sold and an estimated 65% market share. Apple is as pre-eminent in the tablet market as Usain Bolt was in the 100 and 200 meter relay race in the 2008 Olympics or as Secretariat was in winning the 1973 Belmont Stakes. Usain Bolt and Secretariat both so utterly dominated a classy group of competitors that their races were over in the first few strides. Barring an extraordinary mishap on Apple’s part or an incredibly revolutionary product from one of its many rivals, it looks as though the iPad2 has outrun the field and built an insurmountable lead.